The present invention concerns a nutrient composition suitable for enteral feeding (tube feeding). The word "enteral feeding (tube feeding)" used herein means a kind of methods of so-called surgical nutrition used for nutritive care of patients before and after their surgical operation, and it is a method of injecting nutrients via a feeding tube into the gastrointestinal tract of a patient to whom oral feeding of the nutrients is impractical.
The nutrient composition for use in enteral feeding has been classified into elemental diet or chemically defined diet, synthetic low-residue diet and standard blenerized diet.
Elemental diet contains purified crystalline amino acids as the nitrogen source, and nutrient components such as essential fatty acids and vitamins are combined with them. Standard blenderized diet is prepared by combining milk or fruit juice with a fluidized mixture of various kinds of natural food. Synthetic low-residue diet has an intermediate composition of the above-mentioned two categories, and is in a powdery or a liquid state obtained by combining milk casein or egg-albumin as a protein source with fat source, carbohydrate source, inorganic salts and vitamins. It is used after dissolving into water or in an original liquid state.
The nutrient composition of the present invention belongs to the category of the above-mentioned synthetic low-residue diet.
Although various products have hitherto been commerciallized as the nutrient composition for use in enteral feeding, they have the following demerits: (1) they have many side effects causing diarrhea, abdominal pains, feeling of abdominal distension, etc., (2) they cause a raise of transaminase activity, however, only temporarily after administration, (3) their nitrogen balance is not favourable, (4) they taste bad and so are not suitable for oral administration, etc. Indeed, there are some compositions commerciallized with the intention of solving such demerits. For instance, the addition of lipids has been restricted to an extremely low level for control of diarrhea. However, in the case of insufficiency of nutrient supply as a result of aiming the prevention of side effects, such a composition lacks the aptitude as a nutrient.
It is for this reason that the nutrient composition suitable for enteral feeding without causing any side effects such as diarrhea, etc. and with a good taste, which can supply the necessary nutrients sufficiently, has not yet been developed.
On the other hand, the nutrient composition for enteral feeding is also used in the case where the patient is suffering from impairment of deglutition, impassableness through the digestive tracts, etc. in which case there is a necessity of early nutrient supplement after surgical operation, and it is further used in the case where the long term care should be taken on the patient's nutritive state. Accordingly, the provision of a nutrient composition without having the above-mentioned demerits has been strongly demanded.
For reference, the nutrient compositions for enteral feeding hitherto reported or commerciallized are exemplified as follows:
A composition is prepared by combining soy-bean, egg, skim milk, casein and essential amino acids as a protein source; vegetable fats and oils or medium chain triglyceride (MCT, powdery or liquid triglyceride of fatty acid of the medium chain length) as a fat source; and alpha-starch, bread and dextrin as a carbohydrate source, and after adding minerals and vitamins to the composition, it is made to be a liquid state with an addition of water ("SHOKUHIN KOGYO" (Food Industry), Vol. 22(12), page 41, 1979). A composition is prepared by combining skim milk powder, whole milk powder, dextrin, maltose, electrolytes and vitamin. Another composition is prepared by combining dextrin, starch syrup solid, medium chain triglycerides and natural foods. Still another composition is prepared by combining skim milk powder, tricaprylin, lactose and dextrin. (Refer to "RINSHO-EIYOGAKU (Clinical Science of Nutrition) by OKABE, Kazuhiko et al., page 90, published in 1979").
As a result of examination and studying the above-mentioned demerits seen in the publicly known nutrient composition for use in the above-mentioned enteral feeding, the present inventors have confirmed that these dermerits are caused by lactose which is contained in high amount (generally about 52 to 58% by weight) in the skim milk powder used generally as a protein source, the unbalance of amino acid within the protein source in the composition and the insufficiency of the fat content in the composition.
Further, it has been found by the present inventors that the lactose content in the nutrient composition could be reduced by combining 20 to 40% by weight of low-lactose skim milk powder containing a reduced amount of lactose which is obtained by decomposing 50 to 90% by weight of the originally contained lactose, as a kind of protein source and 5 to 15% by weight of medium chain triglyceride (MCT) as a kind of fat source, and that by doing so, the retention of the amino acid balance and the increase of fat content of the composition could be easily carried out by the combination of other protein sources and fat sources. The present invention is based on these findings.
The present invention will be explained in detail as follows: